What is the ride height of the stock STI?
Personally I wouldn't want to go lower than 125mm to 130mm, mainly for driveways and not wanting to eat my bumper for lunch.

As for the alignment, -2.5 and -1.5 front/rear works quite nicely on my car, could go for something more aggressive if you really want to destroy corners...

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2015 Forester XT Premium
2020 VW Tiguan Allspace
teejay: If I wanted a comeback Id wank in front of a fan